Interest in fuel cell batteries as power sources for portable electronic devices has grown. A fuel cell is an electrochemical cell that uses materials from outside the cell as the active materials for the positive and negative electrode. Because a fuel cell does not have to contain all of the active materials used to generate electricity, the fuel cell can be made with a small volume relative to the amount of electrical energy produced compared to other types of batteries.
Fuel cells can be categorized according to the types of materials used in the positive electrode (cathode) and negative electrode (anode) reactions. One category of fuel cell is a hydrogen fuel cell using hydrogen as the negative electrode active material and oxygen as the positive electrode active material. When such a fuel cell is discharged, hydrogen is oxidized at the negative electrode to produce hydrogen ions and electrons. The hydrogen ions pass through an electrically nonconductive, ion permeable separator and the electrons pass through an external circuit to the positive electrode, where oxygen is reduced.
In some types of hydrogen fuel cells, hydrogen is formed from a fuel supplied to the positive electrode side of the fuel cell, and hydrogen is produced from the supplied fuel. In other types of hydrogen fuel cells, hydrogen gas is supplied to the fuel cell from a source outside the fuel cell. A fuel cell system can include a fuel cell battery, including one or more fuel cells, and a hydrogen source, such as a hydrogen tank or a hydrogen generator. In some fuel cell systems, the hydrogen source can be replaced after the hydrogen is depleted. Replaceable hydrogen sources can be rechargeable or disposable.
A hydrogen generator uses one or more reactants containing hydrogen that can react to produce hydrogen gas. The reaction can be initiated in various ways, such as hydrolysis and thermolysis. For example, two reactants can produce hydrogen and byproducts when mixed together. A catalyst can be used to catalyze the reaction. When the reactants react, reaction products including hydrogen gas and byproducts are produced.
For a hydrolysis reaction, the hydrogen generator typically employs a liquid containing a first reactant that mixes with a second solid reactant within a reaction area in a container. A liquid delivery nozzle or dispersing member is typically employed to transport the liquid from a storage area to the reaction area. The liquid delivery nozzle can include a tube having one or more openings through which a liquid passes into the reaction area to mix with the second solid reactant. The reaction causes the generation of hydrogen gas, which exits the hydrogen generator and may be provided as fuel to a fuel cell battery.
It is desirable to provide an effective and efficient utilization of the solid reactant upon reaction with the liquid reactant.